This invention relates to measurement devices, and more particularly to a system and method for determining the tongue weight, gross vehicle weight, and other parameters related to the safe towing of a trailer or other towed vehicle.
The tongue weight of a trailer often varies as a trailer is loaded and unloaded. The determination of tongue weight is key to safe transportation practices since all vehicle hitches have a maximum tongue weight limit. However, the determination of tongue weight in the past has been left largely up to guesswork, thereby compromising safety. If for example the weight on the hitch is too small, the trailer may shimmy and sway possibly causing loss of control and an accident or other catastrophic event. If the weight is too high on the hitch, then the rear of the towing vehicle is overloaded and the steering wheels and brakes are less effective, leading to loss of control of the towing vehicle and the inability to stop the towing vehicle and trailer as anticipated.
Various mechanical and electro-mechanical devices for measuring the tongue weight of a trailer have been proposed. Mechanical-type devices typically include a first structural component that rests on the ground or receiver hitch of a towing vehicle, a second structural member that fits in the tongue of a trailer or other towed vehicle, and a biasing member, such as a compression spring, that biases the first and second structural members apart. As a load is applied to the tongue of the trailer, the second structural component will proportionately move with respect to the first structural component. A stationary scale on the first structural component is proportionately hidden or uncovered depending on the tongue weight. However, such as device is has very limited resolution and often functions as a go-no-go gauge, i.e. either the trailer tongue is overloaded or it is not.
Another solution uses the same principle but relies on hydraulic pressure to drive a gauge with a rotating pointer along a stationary scale. Although this solution provides more accuracy, typically in the range of 50 lbf that can be legibly read, the user is still left guessing as to the exact weight of the tongue. In addition, such devices can only be temporarily used during trailer loading. This is inconvenient to most users since it is desirous to hook the trailer up to the towing vehicle prior to loading. Since some objects to be loaded can be quite heavy, such as farm equipment, ATV's, motorcycles, and so on, there is a danger of the trailer tipping rearwardly if it is not properly coupled to the towing vehicle prior to loading. Accordingly, such sensors in and over themselves become an inconvenience. Moreover, even when such a device can be used, it quickly becomes a nuisance for the user to constantly walk back and forth between the device and the trailer to determine if the trailer tongue is at the proper weight.
In addition, trailers are often rented to customers who typically have little towing experience. Such users typically are not familiar with the dangers of overloading and underloading the tongue weight, exceeding the gross rated weight of the trailer, exceeding the recommended towing speed, sudden braking, going too fast around curved sections of the roadway, towing in inclement weather, and so on. Such unsafe towing conditions can lead to trailer mishaps, loss of property, serious injury, and other catastrophic events. It is often difficult to determine whether or not the driver was at fault or if there was a mechanical failure or weather or road conditions, or combinations thereof, that lead the catastrophic event. Accordingly, investigations to determine liability can be quite costly.
Moreover, vehicle manufacturers typically offer bumper-to-bumper warranties for a predetermined time period and/or up to a predetermined mileage limit, subjected to normal driving conditions. However, when the customer drives the vehicle beyond its intended limits during the warranty period, the manufacturer is often left to cover the costs of repair since, in the past, a quantifying method for determining whether the customer or manufacturer is at fault, has been lacking. This is especially problematic for new vehicles with towing packages. In the past, the vehicle manufacturer or authorized dealer has had to rely heavily on the customer's word that the vehicle being towed did not exceed the manufacturer's guidelines for the maximum tongue weight of the trailer or other towed vehicle and/or the towing capacity of the towing vehicle. This problem is exacerbated by the fact that customers do not have the means for determining the trailer tongue weight or the gross vehicle weight rating of the trailer and the manufacturer. Thus, in many instances, the customer may be acting in good faith without realizing that the towing capacity of the vehicle has been greatly exceeded. When such circumstances occur, warranty items such as the engine, transmission, and/or other drive train components, as well as suspension components, may become damaged and in need of repair or replacement, costs which are necessarily covered by the vehicle manufacturer.
It would therefore be desirous to provide a system and method for determining the tongue weight, gross vehicle weight, and other parameters of the towed vehicle in order to quantify whether or not the towing capacity of the towing vehicle has been exceeded.